OBJECTIVE: Because patients hospitalized in intensive care units are at risk for poor nutrition, and nutritional therapy is not always started at an appropriate time, the present study aimed to correlate nutritional status, early nutrition, and hyperglycemia with patient mortality in an intensive care unit. METHODS: This archival cohort study used the secondary database of 453 patients who stayed at least 48 hours in an intensive care unit and were assessed for 8 days of hospitalization. Patient nutritional status was defined according to the body mass index. Early nutrition was defined as an feeding energy within the first 48 hours of hospitalization, regardless of the administration route. Blood glucose levels were monitored using a glucometer. RESULTS: A majority of patients were male (54.2%), and approximately half of patients were overweight (48.4%). At the end of the first 48 hours, 69.4% of patients had received nutrition, and only 13.5% of patients still exhibited hyperglycemia. The patients who received early nutritional therapy exhibited lower a mortality risk (p = 0.002), regardless of the presence of other factors associated with mortality. CONCLUSIONS: The significant correlation between early nutritional therapy and survival emphasizes the importance of nutrition in severely ill patients. The low frequency of hyperglycemia found in this study might indicate that the prescription of nutritional therapy and the application of an insulin protocol are appropriate at institutional intensive care units.